1. Field of the Invention
The present invention pertains to apparatus for vacuum forming a plastic sheet about a workpiece.
2. Description of the Related Art
As is known in the art, plastic sheets may be softened, and molded about a solid object by laying the plastic sheet over the object and then generating a vacuum thereunder so as to draw the plastic sheet about the workpiece. Heretofore, such machines have been prohibitively costly for hobbyists and for business applications where only a few vacuum formed parts are needed. In addition, such machines have been large and their use made unattractive when the machines are only occasionally required.
As an alternative to large and expensive vacuum forming machines, adaptors have been sold for use with vacuum cleaners. Such adaptors have consisted of a perforated plate with a housing thereunder adapted to be fitted to the flexible hose of a conventional vacuum cleaner. It was contemplated that a user of the adaptor would soften a plastic sheet in an oven, such as that commonly available in a kitchen, and, when softened, the plastic sheet would be carried to the vacuum plate and the vacuum cleaner thereafter energized to produce the necessary vacuum. Such adaptors, however, proved ineffective for some applications, and in general were difficult to use. The heating of a plastic sheet in a remotely located oven and subsequent transport of the softened sheet to the adaptor plate was time-consuming, in the sense that heat from the plastic sheet would be lost to the environment during transport. In addition, it was difficult to accurately align the plastic sheet with the adaptor plate, and a substantial amount of time was often required for an initial draw-down of the sheet against the adaptor plate.